This invention relates to a control apparatus for a hybrid vehicle for setting a motor output value of an electric motor to a value that exceeds a rated performance when an engine is started up only by the electric motor. Miniaturization of the electric motor is also achieved.
Some motor vehicles are of a type commonly called a hybrid vehicle having an internal combustion engine which is driven by combustion of fuel and an electric motor (described hereinafter as xe2x80x9cmotorxe2x80x9d) which is driven by electrical energy and has a power-generating function. The motor is provided to connect with an engine output axis of the engine. The hybrid vehicle further includes an engine control means for controlling a running state of the engine and motor control means for controlling an operating state of the motor. The engine control means and the motor control means detect respective operating states of the engine and the motor when the vehicle is traveling, and then exchange such detected data regarding the running states. As a result, the respective operating states of the engine and the motor are controlled in association with one another. Such a control system attains a high level of required performance (such as fuel efficiency, lower values of detrimental components in exhaust gases, and power performance). In this case, an apparatus includes a battery which supplies drive electricity to a motor and is charged by power-generation of the motor. A required volume of battery charge must be kept in order to perform suitable driving power-generation/driving prohibition for the motor. The apparatus administers the battery.
Moreover, there is a hybrid vehicle with an automatic start-up/stop control means to improve mileage or reduce effluent gas, by forcibly stopping an engine during stopping in an idling state.
One such example of a control apparatus of a hybrid vehicle is disclosed in published Laid-Open Japanese Application No. 9-72266. The vehicle start-up control apparatus of this disclosure possesses an internal combustion engine having a crank shaft, a fuel supply means to save and maintain fuel in a pressure state and to directly supply fuel of predetermined pressure force in a cylinder of the engine, an ignition means to ignite fuel supplied in a cylinder, a pressure force rising means to be driven with the crank shaft and to raise fuel pressure force to a predetermined pressure force. A fuel pressure force detecting means detects fuel pressure force in the fuel supply means. Further, the control apparatus includes a motor connected with the crank shaft for rotating the crank shaft. A rotational changing means raises rotational speed of the motor to increase a fuel pressure force in start-up, when the fuel pressure force detecting means senses decreased fuel pressure. Accordingly, in a vehicle having an internal combustion engine that is directly supplied fuel in a cylinder, a starting-up performance in the state that a fuel pressure force deteriorates is improved. Starting-up performance when an engine temperature of the internal combustion engine is low is also improved.
Another control apparatus is disclosed in published Laid-Open Japanese Application No. 11-187502. The control apparatus for a hybrid vehicle in this disclosure possesses a motor, a first transmitting means which transmits a torque of the motor to a supplementary apparatus and a second transmitting means which transmits a torque of the motor to an internal combustion engine, and controls to stop an internal combustion engine in a vehicle stop and to start up an internal combustion engine with the motor. Further, the control apparatus comprises a clutch means that is arranged in between the motor and the second transmitting means and that can freely change a transmitting torque transmitted by the second transmitting means so that the motor receives a torque. A control means controls the clutch means such that a transmitting torque becomes zero at stoppage of the internal combustion engine, and such that a transmitting torque becomes smaller than the torque that occurs in the motor during internal combustion engine start. Accordingly, in this control apparatus, a low cost is planned, and a supplementary apparatus fully functions.
Incidentally, in a control apparatus for a traditional hybrid vehicle, an electric motor has a performance such that an output is provided at more than a predetermined value, so as to start up an engine by the motor only even at low temperatures.
However, performance to satisfy the engine start-up ability of a motor may not be necessary in other driving states.
If a system not needed for start-up of an engine is considered, there are many good opportunities to miniaturize a motor further.
In order to get adequate starting-up performance, motor size becomes large. Accordingly, the system leads to increased cost and is economically disadvantageous. In addition, as the weight increases, the space efficiency deteriorates. Therefore, as for these negative factors, the motor is disadvantageous in practical use.
Accordingly, an object of this invention is to secure sufficient performance in a driving state, except for start-up, and in a restart-up, to control so as to set a motor output value of an electric motor to a value exceeding the rated performance. Thus a shortage of power is overcome by executing overload driving for a short time.
As amplified later in the detailed description, the present invention provides a control apparatus for a hybrid vehicle having an engine and an electric motor connected to an engine output shaft of the engine mounted on the vehicle. The control apparatus performs an automatic start-up/stop control of the engine. The control apparatus starts the engine using a starter motor in a start-up by operation of a key, and always assists the electric motor. The control apparatus has a control means that controls to drive the electric motor by an engine activation signal so as to start up the engine using only the electric motor, at restarting-up of the engine when a start-up condition is satisfied during operation of an automatic start-up/stop control of the engine. The control means controls to drive the starter motor and the electric motor outputs an engine activation signal so as to always assist by using the electric motor when starting up with the starter motor, at restarting-up of the engine when a start-up condition is not satisfied during operation of an automatic start-up/stop control of the engine. The control means sets a motor output value of the electric motor to a value exceeding a rated performance when the engine restarts up by using only the electric motor. Accordingly, using the control means, the total time necessary to decide performance of the electric motor is short, but performance of the electric motor can be decided without adapting to a needed performance at start-up when high performance is necessary. Accordingly, miniaturization of the electric motor (because the performance necessary for the assist control that is a main purpose is not higher than a requirement at start-up) can be achieved. Space efficiency for carrying and mounting the motor in limited spaced in engine rooms and the like can be improved. The space efficiency that is a ratio to mount in limited space of engine rooms and the like can be improved. The whole system is capable of having a lighter weight. As a result, this system can contribute to improvement of exhaust gas purification performance and fuel efficiency performance.
In addition, the present invention provides a control apparatus for a hybrid vehicle having an engine and a electric motor connected to an engine output shaft. The control apparatus performs an automatic start-up/stop control of the engine, and suitably assists the electric motor. The control apparatus has a control means that controls the electric motor, which is arranged in between the engine and a transmission. The control apparatus executes overload driving of the electric motor when starting up the engine. Accordingly, in this system, as both vehicle types mounted with an engine only or a hybrid engine can be set to execute overload driving at a start-up of the engine. If size of the motor (depth and diameter direction) gives great influence to size of an engine room, the size of the motor can be suited to reasonable size and have enough performance to assist driving, and overload driving at start-up when enabled. As a result, this system can utilize a motor compact in size, and is advantageous in practical use.
Moreover, the control means controls the electric motor, which is arranged between the engine and transmission, so as to, when starting up the engine, execute overload driving. Thus the size of the motor can be a reasonable size to assist driving and so that overload driving at start-up is enabled. As a result, this system provide a small compact size for the motor